This invention relates in general to internal combustion engines and other devices that generate a flow of exhaust gas or liquid during use. More specifically, this invention relates to a simple and accurate apparatus and method for sampling and analyzing such exhaust gas or liquid.
Sensors are commonly used in the exhaust systems of internal combustion engines and other devices that generate a flow of exhaust gas or liquid during use in order to measure a variety of parameters, such as an air-to-fuel ratio of the exhaust gas. One common method of sensor installation is to drill a hole in a portion of the exhaust system, then weld a nut (sometimes referred to as a bung) over the hole such that a sensor can be screwed through the nut and the hole into the portion of the exhaust system to measure the desired parameter. In another common method, the sensor is attached to a tube that, in turn, is inserted into a tailpipe or other output component of the exhaust system to measure the desired parameter.
Although the known methods have been effective, several disadvantages have been noted. The welded bung method permits the sensor to make relatively accurate measurements, but involves the use of specialized tools and a knowledgeable installer. Therefore, the welded bung method is relatively complicated and expensive to perform. The tailpipe insertion method, on the other hand, is much simpler and inexpensive to perform, but can be less accurate because of the potential for exhaust gas reversion, which can cause the sensor to be exposed to a mixture of the exhaust gas with ambient air from outside the tailpipe. This can occur because many tailpipes have baffles or bends that can make it difficult to insert a tube sufficiently far within the tailpipe to avoid the effects of reversion. Thus, it would be desirable to provide a simple and accurate apparatus and method for sampling and analyzing the exhaust gas or liquid generated from an internal combustion engine or other device that avoids these problems.